There is a variety of copper base alloys that are used in connector, lead frame and other electrical applications because their special properties are suitable for these applications. However, there is a need for copper base alloys that can be used in applications that require high yield strength in the order of 80-100 KSI, together with good forming properties that allow one to make 180.degree. badway bends with a R/T ratio of 1 or less plus good electrical conductivities of 30% or better, plus low relaxation of stress at elevated temperatures and freedom of stress corrosion cracking. These represent a highly desirable combination of properties. Alloys presently available do not meet all of these requirements or have high costs that make them less economical in the marketplace or have other significant drawbacks. It is highly desirable to develop a copper base alloy satisfying the foregoing goals.
Beryllium copper generally has very high strength and conductivity along with good stress relaxation characteristics; however, these materials are limited in their forming ability. One such limitation is the difficulty with 180.degree. badway bends. In addition, they are very expensive and often require extra heat treatment after preparation of a desired part. Naturally, this adds even further to the cost.
Phosphor bronze materials are inexpensive alloys with good strength and excellent forming properties. They are widely used in the electronic and telecommunications industries. However, they tend to be undesirable where they are required to conduct very high current under very high temperature conditions, such as for example under conditions found in automotive applications for use under the hood. This combined with their high thermal stress relaxation rate makes these materials less suitable for many applications.
High copper high conductivity alloys also have many desirable properties, but generally do not have mechanical strength desired for numerous applications. Typical of these alloys include but are not limited to copper alloys 110, 122, 192 and 194.
Representative prior art patents include U.S. Pat. Nos. 4,666,667, 4,627,960, 2,062,427, 4,605,532, 4,586,967 and 4,822,562.
Accordingly, it is highly desirable to develop the copper base alloys having a combination of desirable properties making them eminently suitable for many applications.